Hard disk drives (HDDs) used as storages for computers are inspected before shipment by various methods to ensure high quality. No little inspecting methods cost very much, such as an operation inspection in a low-temperature environment that requires a dedicated facility.
To prevent the cost of inspection to increase, there may be used a model to predict the possibility of pass or failure in advance. If a prediction model yields a prediction result on a product that the product is highly likely found passed or failed, it is determined that a high-cost inspection of the product is unnecessary to implement, and another, low-cost inspection is implemented instead of the high-cost inspection. This method makes it possible to reduce the number of targets to be subjected to the high-cost inspection while ensuring quality.
For the prediction model, parameters (prediction parameters) used for the prediction matters. This is because the prediction parameters closer to optimum values bring an improved accuracy of the prediction. However, to bring the prediction parameters closer to the optimum value, a large number of predictions and inspection results are needed, entailing a high cost.
In addition, as to HDDs, it is often the case where configuration conditions such as design values and members are modified even in the same type. In this case, using a prediction model corresponding to a configuration before the modification results in the reduction of prediction accuracy. This is because the modification of the configuration conditions causes the optimum values of the prediction parameters to be changed. Therefore, after the modification of the configuration conditions, it is necessary to update the prediction parameters early enough. It is however required to implement a high-cost inspection therefor, involving a problem of increasing cost.